This invention is directed to a mattress core and a mattress formed therefrom. Typical of such conventional structures is that disclosed in the patent to Awdhan (U.S. Pat. No. 4,673,452) which discloses a central polyurethane foam core and opposite convoluted layers with the entire mattress being bounded by side pieces and end pieces in the form of a conventional so-called racetrack mattress. The entirety of the mattress and mattress core is constructed from synthetic polymeric/copolymeric plastic material.
Another typical mattress is that disclosed in the patent to May (U.S. Pat. No. 5,701,623) which includes a center core of latex foam rubber having a generally polygonal outline defined by relatively short parallel foot and head faces and relatively longer parallel side faces. A border is formed by four border sections with side border sections being bonded to the side faces of the core and foot and head border sections being bonded to respective foot and head faces of the core. Opposite end faces of the side border sections are overlapped by the respective head and foot border sections. The border sections are preferably constructed from urethane foam having a range of density or Initial Load Deflection (ILD) less than the density or the ILD of the latex foam rubber of the core which results in a border of a mattress being firmer than the center core.
The latter mattress cores/mattresses provide certain advantages yet neither or a combination thereof seemingly achieves the most important characteristic desired in a mattress, particularly a mattress associated with healthcare installations, such as hospitals, nursing homes, etc., which is the minimization of body pressure, such as would provide pressure relief which would maximize capillary blood flow and/or prevent bed sores.
The patent to Boyd et al. (U.S. Pat. No. 5,636,397) discloses a futon mattress which includes two convoluted sections, as in the Awdhan patent, but rails are disclosed only at ends of the convoluted sheets or layers. However, this patent and the others mentioned reference desirability of different materials for different components of the mattress which has different density and/or ILD ranges, as well as convoluted and/or non-convoluted plies or layers to achieve desired firmness or zoned areas of firmness. Further examples of such mattress/mattress core constructions can be found in the following patents:
Hood U.S. Pat. No. 3,118,153
Pollock U.S. Pat. No. 3,210,781
Cohen U.S. Pat. No. 3,521,311
Miller U.S. Pat. No. 3,774,250
Hall et al. U.S. Pat. No. 3,939,508
Rogers U.S. Pat. No. 4,042,987
Talbert et al. U.S. Pat. No. 4,086,675
Masuda U.S. Pat. No. 4,143,435
Evans et al. U.S. Pat. No. 4,975,996
Kraft U.S. Pat. No. 4,999,868
Fenner. Sr. U.S. Pat. No. 5,022,111
Kraft U.S. Pat. No. 5,136,740
Masuda U.S. Pat. No. 5,138,730
Masuda U.S. Pat. No. 5,172,436
Loving et al. U.S. Pat. No. 5,353,455
Ward U.S. Pat. No. 6,202,239 B1
A mattress core or mattress constructed in accordance with this invention includes a center core of a generally polygonal configuration formed of latex foam and upper and lower latex foam outer layers of latex foam having exterior convoluted surfaces defined by peaks and valleys. The outer layers are bonded to the base core and a polyurethane foam side rail is located one along each base core and side surfaces of the upper and lower layers. The side rails are bonded to at least one of the base core and the outer layer side surfaces and each side rail preferably has a height corresponding substantially to the distance between valleys of convolutions of the opposite outer layers. The ends of the base core and the outer layers define terminal end surfaces of the mattress core/mattress which are devoid of any rails.
Preferably the mattress core/mattress have an ILD range of substantially 26 ILD to 50 ILD for the side rails, 24 to 40 ILD for the base core and 12 to 45 ILD for each of the outer layers.
The base core and the outer layers also collectively define a torso firmness zone and opposite head and foot firmness zones with the torso firmness zone being substantially between 20 percent (20%) to 30 percent (30%) more dense than the head and foot firmness zones.
With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings.